Using the Blow Molder


The Blow-Molding machine is located in laboratory 109A of the John Mitchell Center.  Blow molding is a process for forming hollow objects from thermoplastics.  Products such as bottles, garbage cans, and toys are common. 

This document describes the operation of the blow-molder and safety practices.


Blow Molder Operation:

Caution:  Follow these directions exactly to avoid damage to this equipment.

1. Be sure all switches are in "OFF" position and that key is removed from Extruder Switch.

2. Plug in molder, compressed air, and water supply tube.

3. Check to make sure water is running (it can be running very slow).

4. Open mold far enough to make contact with micro switch.  This allows the extruder to run.

5. Turn barrel and die heater switches to "on".

6. Set barrel and die heat regulators to "50" which corresponds to approximately 300 degrees Fahrenheit.

7. Adjust barrel and die tempatures to 300 degreees by turning regulators down if tempature exceeds 300 degrees or by turning up if pilot light goes out at less than 300 degrees.

8. Make sure plastic is in the hopper and that the feed slide gate is open.

9. Turn air on and adjust to 5 to 15 PSI.

10. Only after barrel and die reaches 300 degrees Fahrenheit, turn on the extruder key.

11. If the extruder does not run, open mold further, to ensure that the micro-switch has made contact.

12. When the parison is approximately 1/2" below the mold, close mold and turn Blow Switch to "on" for approximately 10-15 seconds.

13. Open mold to remove product. (If right mold half is only partially opened, extruder will not operate.)

14. Fully open mold to extrude new parison.

Blow Molder Shutdown/Safety:

1. Turn off and remove extruder key.

2. Turn off die, barrel, and master switch.

3. Turn off air.

4. Do Not turn of water until barrel and die have cooled below 105 degrees (approximately one hour).

5. Ask for assistance if you are not sure how to operate the blow molder.

6. Do not process materials in the blow molder if you do not know how they will react.

7. Have a fire extinguisher handy when using the blow molder.

8. Wear safety glasses when using the blow molder.

9. Wear thermal gloves or use handling tools when removing hot materials.

10. Do not leave the blow molder unattended when in use.

Miller, W. R. (1978) Plastics Industrial Arts Illinois:  McKnight Publishing Company
Brent Strong A. (1996) Plastics Materials and Processing New Jersey:  Simon & Shuster
Prepared by Marcel Dube, 3/25/98